A conception of runoff‐phenomena

The problem of transforming observed precipitation into stream‐flow for a natural drainage‐basin can be divided into two parts. The first part requires a procedure for determining the amount and kind of runoff that occurs under various conditions. The second part is concerned with the shaping of the runoff into a discharge‐hydrograph for a particular gaging station. (Rainfall‐eccentricities often provide more difficulties than either of the above.)

Considerable investigation has been made and is being continued along both lines of research. The unit‐hydrograph and related methods now provide a means of shaping discharge‐hydrographs as accurately as is required by the practical considerations of most problems. However, it is believed that methods for determining the amount and kind of runoff which occur under various conditions have not been demonstrated to an equivalent refinement. It is with the latter problem that this paper is concerned.